Running defense

They started well but have allowed at least 100 yards rushing in each of the last five games. Their defense suffered a noteworthy but not necessarily devastating blow two weeks ago when middle linebacker Brian Urlacher’s injured a hamstring, which appears likely to have ended his season. The 34-year-old Urlacher was playing on a deteriorating knee, and though he remained a good player because of his intelligence and instincts, he wasn’t the playmaker of his younger years or even last season.

To replace him, Nick Roach (6-1, 234) moves from the strong side to the middle, and Geno Hayes (6-1, 226) starts on the strong side. Roach is faster than Urlacher but not as stout. Hayes likewise is smaller, faster and more athletic than Roach but not as stout.

Passing defense

The strength is their line, where they have quality and quantity, and they also are one of the NFL’s best at forcing turnovers, or at least were earlier in the season. End Julius Peppers (seven sacks) is their best player, and the second-best might be ascending tackle Henry Melton (six sacks), who’s become one of the best inside rushers in the league but is listed as doubtful to play today because of a chest injury.

Israel Idonije and Corey Wootton (51/2 sacks each) are decent power-oriented outside rushers as well. The Bears lead the league in interceptions with 21 but have had only four in the last five games, and are 1-4 over that span.

Undersized cornerback Tim Jennings (5-8, 195) has been a playmaker (his eight interceptions leads the NFL) and is listed as out for today's game with a concussion.

Cornerback Charles Tillman, 31, is master of the strip after the catch and has forced an amazing nine fumbles this season. The Bears’ play at safety has been much better than the past few years because second-year pro Chris Conte’s (6-2, 203) awareness improved from his rookie season, and Major Wright (four interceptions) has played the best football of his three-year career.

Special teams

First-rate kicker Robbie Gould injured a calf in pregame warmups last week, handled only extra points and was placed on injured reserve Tuesday. The Bears replaced him with 39-year-old Olindo Mare, who’s made 81.2 percent of his career field-goal attempts but has been out of football this season after kicking for Carolina last year.

Punter Adam Podlesh ranks No. 19 in net average (39.2 yards) and No. 31 in gross (41.8 yards). Hester is handling the majority of returns and remains a scary sight back on punts and kickoffs, though he hasn’t broken a long one on either this year. He’s averaging 25.5 yards on kickoffs (long of 38 yards) and 8.5 yards on punts (long of 44 yards).